Queremos dar las gracias a Arumae Urmas para compartir un protocolo de colágeno y Fey y Jutta Hinz Ursula por su excelente asistencia técnica. Además queremos agradecer a Christian F. Ackermann, Ulrike Engel y la Nikon Imaging Center en la Universidad de Heidelberg y también por la amabilidad de Joachim Kirsch ayuda para el shoting video. El trabajo fue financiado parcialmente a través de la Deutsche Forschungsgemeinschaft (SFB 592).

1. Preparación de geles de colágeno <ol><li> Preparar un medio de acción, que contiene 455 l MEM 10x, 112 l 7,5% NaHCO 3, 50 y glutamina l NaOH. La concentración y la cantidad de la solución de NaOH depende de la preparación de colágeno de cola de rata (ver 1,2), el volumen final del medio de archivo de ser 1.000 l. </li><li> Preparar colágeno de cola de rata de acuerdo con Ebendal (1). Almacenar la solución de colágeno a 4 ° C. Una degradación de la solución de colágeno no se puede observar. Después de la preparación de un nuevo lote, estimar la concentración de NaOH necesaria para el medio de almacén (ver 1,1). Utilice el indicador de pH del medio para la valoración de la cantidad y la concentración de NaOH. 800 l ácido de cola de rata colágeno tiene a su vez un tono de rojo cuando se mezcla con 210 l de la media de valores. Si la concentración de NaOH es demasiado baja, la solución de colágeno se volverá amarilla, debido a que el indicador de pH del medio. Añadir el colágeno al medio y se mezcla sin producing burbujas. Realice estos pasos en el hielo. La polimerización se produce dentro de 2 horas después de la solución de colágeno y el medio de archivo se han mezclado y la nueva solución se incuba a 37 ° C. Pruebe esto antes de comenzar el experimento. 1,3) Mezclar 800 l de solución de colágeno con l 210 de media de valores (ver 1.2). Place 100 l de esta solución en los pocillos de una diapositiva cámara 8 también. Incubar los portas a 37 ° C, 5% de CO 2 y condiciones de humedad en una incubadora de cultivo celular. Preparar los geles de colágeno bajo un banco de cultivo celular y las condiciones estériles. El colágeno gelatiniza dentro de 2 h. </li></ol> 2. Disección de SCG embrionarias <ol><li> Cosecha embriones de ratones preñados de tiempo (E16-18) desde el útero y los mantienen en PBS hasta que se necesita más. </li><li> Disecciona un embrión desde el amnios. Decapita el caudal del embrión nivel clavicular. Fijar la cabeza en una bandeja inferior de silicio con &quot;insecto-agujas&quot;. El lado ventral de la cabeza tiene que enfrentarse a usted unad que tiene que ver la región submandibular. La fijación permite una preparación más fácil. </li><li> Quitar la piel de la región submandibular izquierda y derecha, y con ella el tejido conectivo subcutáneo. </li><li> Retire las glándulas salivales submandibulares de su ubicación para despejar la vista hacia el hioides, los músculos infrahyoidal y el músculo esternocleidomastoideo. </li><li> Retire con cuidado estos músculos para borrar la vista hacia la laringe y la tráquea. Eliminar la tráquea y la laringe. Las arterias carótidas son entonces visible por ambos lados en los músculos prevertebral. El SCG se encuentra en la bifurcación de las arterias carótidas y tiene una forma oval. Retire con cuidado los ganglios y colocarlos en PBS. Retire los ganglios suavemente de las herramientas de disección si se adhieran a ellos. Es beneficioso el uso de fórceps, así como un soporte de aguja montada con una &quot;aguja insecto&quot; para la eliminación SCG. </li><li> Una vez en PBS, los ganglios almacenar a temperatura ambiente en PBS hasta que se diseccionaron enoulos ganglios de la GH. A continuación, limpie los ganglios de los vasos sanguíneos y tejido conectivo. Realizar la disección de SCG y la limpieza bajo un microscopio de disección coloca bajo una cabina de flujo laminar. </li><li> Finalmente, colocar los ganglios explantados en los geles de colágeno gelatinizados con la ayuda de agujas de jeringa montada en una jeringa para un manejo más fácil. </li><li> Incubar los explantes CGS en el colágeno gelatinizado en una incubadora de cultivo celular a 37 º C, con condiciones de 5% de CO 2 y húmedo. </li></ol> 3. El tratamiento de los explantes de SCG <ol><li> Después de 1-2 horas de incubación, el colágeno cubrir explante SCG que contiene 100 l con medio Neurobasal cultivo celular que contenía suplemento B27, glutamina y antibióticos. Ahora los pocillos de los portaobjetos de cámara de contener un volumen de 200 l (100 gel l y 100 l medio). Añadir otra l 200 del medio, sin embargo, ahora que contiene NGF (60 ng / ml) para facilitar el crecimiento axonal. En consecuencia, la concentración de NGF final es 30 ng / ml. </li><li><ol class="lalpha"><li> Para investigar la aparición de SC migración, añadir factores adicionales directamente en días in vitro 0 (DIV0). Disolver los factores en el medio que contiene NGF en la concentración necesaria doble (2). </li><li> Con el fin de analizar el impacto en la SC, que ya comenzaron a emigrar a lo largo de los axones, agregan factores adicionales en DIV3 hasta DIV4 (parada potencial del experimento). Con este fin, retirar cuidadosamente 180 ml ​​de la solución, en DIV3, y añadir 200 l NGF medio nuevo que contenía y los factores adicionales de interés en la concentración doble (2). </li></ol></li></ol> 4. Time-lapse de imágenes El uso de un microscopio invertido para los análisis. Objetivos pueden utilizar diversos, definir el campo de visión y la ampliación. Un aspecto importante, sin embargo, es la distancia de trabajo del objetivo utilizado, como formación de imágenes de los explantes SCG se realiza a través de la lámina de vidrio y el colágenogel. La velocidad de grabación de 1/10-30 minutos mostró buenos resultados (2). Sin embargo, este aspecto tiene que ser ajustado a la pregunta científica. Un normal cámara CCD puede ser utilizado para la adquisición de imágenes. Para una imagen en tiempo lapso de un cultivo celular cámara de incubación tiene que ser unida a la platina del microscopio. Incubar el tejido durante la formación de imágenes a 37 ° C, con condiciones de 5% de CO 2 y húmedo. Iniciar el sistema de incubación de una hora antes del inicio de formación de imágenes. Esto permite que las partes de microscopio (por ejemplo objetivo), incluyendo la cámara de diapositivas para ajustar a la temperatura y evita las derivas de temperatura inducidas. Definir áreas específicas de análisis (en el explante y entre diferentes explantes) con la ayuda del software del microscopio y una etapa motorizada controlada por software (configuración multiposición) para análisis simultáneos de diferentes condiciones aplicadas a los explantes de SCG. Para el tiempo de imágenes a intervalos de tejido de tipo salvaje así como el tejido de los animales transgénicos se pueden utilizarmarcando el SCS (S100B: GFP) (3). Para fluoróforos de formación de imágenes de una fuente de luz fluorescente tiene que ser aplicado en la configuración micropscope. Usa los filtros estándar. 5. Cuantificación de SC distancias de migración <ol><li> En el punto final (por ejemplo DIV4), fijar los geles de colágeno con 4% de PFA en el portaobjetos para cámara de 3-4 horas. Consecutivamente lavar los geles de colágeno 5 veces durante 10 min con PBS. Aplicar protocolos estándar para inmunocitoquímica (2). Si es nuevo para la preparación de SCG, verificar la identidad del ganglio como un ganglio simpático por inmunohistoquímica contra la tirosina hidroxilasa (TH) un marcador común para las células catecolaminérgicas. Durante inmunohistoquímica (después de que el anticuerpo primario), la transferencia de los geles de colágeno que contiene explantes a placas de 24 pocillos, que tienen un mayor volumen, lo cual es beneficioso para el lavado de los geles. </li><li> Después de inmunohistoquímica, coloque cuidadosamente los geles de colágeno en portaobjetos de vidrio. Cuidadosamenteeliminar la solución remanente y dejar que el colágeno seco / reducir a dos dimensiones. Esto permite facilitar las medidas de distancias (2). Después de esto, montar las muestras. </li><li> Por último, medir distancias de migración con la ayuda de Fiji (NIH) de software. No hay plugins especiales son necesarias para este fin. Para permitir que las mediciones correctas en micras, comprobar los metadatos de imagen correcta y la configuración en el Fiji, la imagen y la escala. Use Fiji también para la cuantificación de las células. </li></ol>

<ol>
	<li>Ebendal, T., Rush, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Use of collagen gels to bioassay nerve growth factor activity. IBRO Handh, (1989).</li><li>Heermann, S., Schm&#195;cker, J., Hinz, U., Rickmann, M., Unterbarnscheidt, T., Schwab, M. H., Krieglstein, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuregulin+1+type+III/ErbB+signaling+is+crucial+for+Schwann+cell+colonization+of+sympathetic+axons.">Neuregulin 1 type III/ErbB signaling is crucial for Schwann cell colonization of sympathetic axons.</a> PloS One. 6 (12), e28692 (2011).</li><li>Zuo, Y., Lubischer, J. L., Kang, H., Tian, L., Mikesh, M., Marks, A., Scofield, V. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescent+proteins+expressed+in+mouse+transgenic+lines+mark+subsets+of+glia,+neurons,+macrophages,+and+dendritic+cells+for+vital+examination.">Fluorescent proteins expressed in mouse transgenic lines mark subsets of glia, neurons, macrophages, and dendritic cells for vital examination.</a> The Journal of Neuroscience. The Official Journal of the Society for Neuroscience. 24 (49), 10999-11009 (2004).</li><li>Levi-Montalcini, R., Booker, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EXCESSIVE+GROWTH+OF+THE+SYMPATHETIC+GANGLIA+EVOKED+BY+A+PROTEIN+ISOLATED+FROM+MOUSE+SALIVARY+GLANDS.">EXCESSIVE GROWTH OF THE SYMPATHETIC GANGLIA EVOKED BY A PROTEIN ISOLATED FROM MOUSE SALIVARY GLANDS.</a> Proceedings of the National Academy of Sciences of the United States of America. 46 (3), 373-384 (1960).</li><li>Meintanis, S., Thomaidou, D., Jessen, K. R., Mirsky, R., Matsas, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+neuron-glia+signal+beta-neuregulin+promotes+Schwann+cell+motility+via+the+MAPK+pathway.">The neuron-glia signal beta-neuregulin promotes Schwann cell motility via the MAPK pathway.</a> Glia. 34 (1), 39-51 (2001).</li><li>Yamauchi, J., Miyamoto, Y., Chan, J. R., Tanoue, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ErbB2+directly+activates+the+exchange+factor+Dock7+to+promote+Schwann+cell+migration.">ErbB2 directly activates the exchange factor Dock7 to promote Schwann cell migration.</a> The Journal of cell biology. 181 (2), 351-365 (2008).</li><li>Anton, E. S., Weskamp, G., Reichardt, L. F., Matthew, W. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nerve+growth+factor+and+its+low-affinity+receptor+promote+Schwann+cell+migration.">Nerve growth factor and its low-affinity receptor promote Schwann cell migration.</a> Proceedings of the National Academy of Sciences of the United States of America. 91 (7), 2795-2799 (1994).</li><li>Mahanthappa, N. K., Anton, E. S., Matthew, W. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glial+growth+factor+2,+a+soluble+neuregulin,+directly+increases+Schwann+cell+motility+and+indirectly+promotes+neurite+outgrowth.">Glial growth factor 2, a soluble neuregulin, directly increases Schwann cell motility and indirectly promotes neurite outgrowth.</a> The Journal of Neuroscience: The Official Journal of the Society for Neuroscience. 16 (15), 4673-4683 (1996).</li><li>Yamauchi, J., Chan, J. R., Shooter, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurotrophins+regulate+Schwann+cell+migration+by+activating+divergent+signaling+pathways+dependent+on+Rho+GTPases.">Neurotrophins regulate Schwann cell migration by activating divergent signaling pathways dependent on Rho GTPases.</a> Proceedings of the National Academy of Sciences of the United States of America. 101 (23), 8774-8779 (2004).</li><li>Gumy, L. F., Bampton, E. T. W., Tolkovsky, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyperglycaemia+inhibits+Schwann+cell+proliferation+and+migration+and+restricts+regeneration+of+axons+and+Schwann+cells+from+adult+murine+DRG.">Hyperglycaemia inhibits Schwann cell proliferation and migration and restricts regeneration of axons and Schwann cells from adult murine DRG.</a> Molecular and Cellular Neurosciences. 37 (2), 298-311 (2008).</li><li>Sakaue-Sawano, A., Kurokawa, H., Morimura, T., Hanyu, A., Hama, H., Osawa, H., Kashiwagi, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+spatiotemporal+dynamics+of+multicellular+cell-cycle+progression.">Visualizing spatiotemporal dynamics of multicellular cell-cycle progression.</a> Cell. 132 (3), 487-498 (2008).</li><li>Park, D., Don, A. S., Massamiri, T., Karwa, A., Warner, B., MacDonald, J., Hemenway, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+imaging+of+cell+death+using+an+Hsp90+ligand.">Noninvasive imaging of cell death using an Hsp90 ligand.</a> Journal of the American Chemical Society. 133 (9), 2832-2835 (2011).</li><li>Shcherbo, D., Souslova, E. A., Goedhart, J., Chepurnykh, T. V., Gaintzeva, A., Shemiakina, I. I., Gadella, T. W. J., Lukyanov, S., Chudakov, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Practical+and+reliable+FRET/FLIM+pair+of+fluorescent+proteins.">Practical and reliable FRET/FLIM pair of fluorescent proteins.</a> BMC Biotechnology. 9, 24 (2009).</li></ol>

No hay conflictos de interés declarado.

El desarrollo del sistema nervioso periférico es un proceso excitante. Cuando el desarrollo se ha completado, los axones se envainado por SCS a lo largo de toda la longitud, que puede, en los seres humanos, a menudo ser más de 100 cm. Para este fin, el número correcto de los CSs requeridas tiene que ser establecido durante el desarrollo y los SCS también tienen que moverse a lo largo de los axones que se extienden a la periferia para asegurar la cobertura completa axonal. Esto es válido para los axones mielinizados...

<table border="1"><tbody><tr><td> Nombre del reactivo / material </td><td> Empresa </td><td> Número de catálogo </td><td> Comentarios </td></tr><tr><td> MEM 10 veces </td><td> Gibco </td><td> 21430 </td><td></td></tr><tr><td> Bicarbonato de sodio (7,5%) </td><td> Gibco </td><td> 25080 </td><td></td></tr><tr><td> Glutamina </td><td> Gibco </td><td> 25030 </td><td></td></tr><tr><td> NaOH </td><td> Merck </td><td> 109137 </td><td></td></tr><tr><td> NGF </td><td> Roche </td><td> 1058231 </td><td> De I + D # 556-NG-100 </td></tr><tr><td> Medio Neurobasal </td><td> Gibco </td><td> 21103 </td><td></td></tr><tr><td> B27 Suplemento </td><td> Gibco </td><td> 17504 </td><td></td></tr><tr><td> antibióticos </td><td> Gibco </td><td> 15640 </td><td></td></tr><tr><td> D-PBS </td><td> Gibco </td><td> 14040 </td><td></td></tr><tr><td> agujas de insectos </td><td> FST </td><td> 26002-20 </td><td></td></tr><tr><td> jeringa con aguja </td><td> Braun </td><td></td><td> BD # 300013 </td></tr><tr><td> 8 Deslice la cámara bien </td><td> Lab Tek </td><td> 177402 </td><td></td></tr></tbody></table>

analyzing murine schwann cell development along growing axons

El desarrollo de los nervios periféricos es un proceso intrigante. Las neuronas envían axones inervan a los objetivos específicos, que en los seres humanos son a menudo más de 100 cm de distancia del soma de la neurona. La supervivencia neuronal durante el desarrollo depende de factores de crecimiento derivados de meta-, sino también sobre el soporte de las células de Schwann (SCS). Para este axones ensheath finales SC de la región del soma neuronal (o la transición de la central en el sistema nervioso periférico) a la sinapsis o unión neuromuscular. Células de Schwann son derivados de la cresta neural y migran como precursores a lo largo de los axones emergentes hasta el axón está cubierto con SCS. Esto muestra la importancia de la SC de migración para el desarrollo del sistema nervioso periférico y subraya la necesidad de investigar este proceso. Con el fin de analizar SC desarrollo, una configuración que se necesita al lado de los SCS también incluye su sustrato fisiológico para la migración, el axón. Debido al desarrollo intrauterino <em&gt; in vivo imágenes a intervalos de tiempo, sin embargo, no es factible en los vertebrados placentarios como el ratón (Mus musculus). Para evitar esto, hemos adaptado el superior ganglio cervical (SCG) Técnica de explante. Tras el tratamiento con factor de crecimiento nervioso (NGF) explantes SCG extender axones, seguido de precursores SC migran a lo largo de los axones del ganglio de la periferia. La belleza de este sistema es que el SC se derivan de una piscina de SC endógeno y que migran a lo largo de sus axones propios fisiológicos que están creciendo, al mismo tiempo. Este sistema es especialmente interesante, ya que el desarrollo SC largo de los axones pueden ser analizados por time-lapse, abriendo nuevas posibilidades para obtener información sobre la migración SC.

El crecimiento axonal se facilita de SCG explantes tras el tratamiento con NGF (4) (esquema película S1 Figura 1 esquema). Este proceso es fácilmente visible por cualquier microscopio invertido y puede ser seguido por imagen de lapso de tiempo (película S2). Si un científico es algo nuevo para la disección de SCG de embriones de ratón es muy recomendable una validación de la técnica por un simple anti-tirosina hidroxilasa (TH) inmunohistoquímica. TH es un marcador común para l...

Watch this Scientific Journal Video about Analyzing Murine Schwann Cell Development Along Growing Axons at JoVE.com

Analyzing Murine Schwann Cell Development Along Growing Axons

Aquí se describe una célula de Schwann (CS) ensayo de migración en el que las SC son capaces de desarrollar a lo largo de los axones se extienden.

Analizar el desarrollo de células murinas Schwann largo de los axones en crecimiento

The  development of peripheral nerves is an intriguing process. Neurons send out  axons to innervate specific targets, which in humans are often more than ...

analyzing-murine-schwann-cell-development-along-growing-axons

Research

JoVE Journal

Neuroscience

11.6K vistas.  University of Freiburg. Aquí se describe una célula de Schwann (CS) ensayo de migración en el que las SC son capaces de desarrollar a lo largo de los axones se extienden.

Video: Analyzing Murine Schwann Cell Development Along Growing Axons

Live Imaging of Dorsal Root Axons after Rhizotomy

The primary sensory axons injured by spinal root injuries fail to regenerate into the spinal cord, leading to chronic pain and permanent sensory loss. Regeneration of dorsal root (DR) axons into spinal cord is prevented at the dorsal root entry zone (DREZ), the interface between the CNS and PNS. Our understanding of the molecular and cellular events that prevent regeneration at DREZ is incomplete, in part because complex changes associated with nerve injury have been deduced from postmortem analyses. Dynamic cellular processes, such as axon regeneration, are best studied with techniques that capture real-time events with multiple observations of each living animal. Our ability to monitor neurons serially in vivo has increased dramatically owing to revolutionary innovations in optics and mouse transgenics. Several lines of thy1-GFP transgenic mice, in which subsets of neurons are genetically labeled in distinct fluorescent colors, permit individual neurons to be imaged in vivo1. These mice have been used extensively for in vivo imaging of muscle2-4 and brain5-7, and have provided novel insights into physiological mechanisms that static analyses could not have resolved. Imaging studies of neurons in living spinal cord have only recently begun. Lichtman and his colleagues first demonstrated their feasibility by tracking injured dorsal column (DC) axons with wide-field microscopy8,9. Multi-photon in vivo imaging of deeply positioned DC axons, microglia and blood vessels has also been accomplished10. Over the last few years, we have pioneered in applying in vivo imaging to monitor regeneration of DR axons using wide-field microscopy and H line of thy1-YFP mice. These studies have led us to a novel hypothesis about why DR axons are prevented from regenerating within the spinal cord11.
In H line of thy1-YFP mice, distinct YFP+ axons are superficially positioned, which allows several axons to be monitored simultaneously. We have learned that DR axons arriving at DREZ are better imaged in lumbar than in cervical spinal cord. In the present report we describe several strategies that we have found useful to assure successful long-term and repeated imaging of regenerating DR axons. These include methods that eliminate repeated intubation and respiratory interruption, minimize surgery-associated stress and scar formation, and acquire stable images at high resolution without phototoxicity.

An in vivo imaging protocol to monitor primary sensory axons following dorsal root crush is described. The procedures utilize wide-field fluorescence microscopy and thy1-YFP transgenic mice, and permit repeated imaging of axon regeneration over 4 cm in the PNS and axon interactions with the interface of the CNS.

Imágenes en vivo de los axones de la raíz dorsal después de rizotomía

The primary sensory axons injured by spinal root injuries fail to regenerate into the spinal cord, leading to chronic pain and permanent sensory loss. ...

Investigación

Neurociencias

Single-cell Profiling of Developing and Mature Retinal Neurons

Highly specialized, but exceedingly small populations of cells play important roles in many tissues. The identification of cell-type specific markers and gene expression programs for extremely rare cell subsets has been a challenge using standard whole-tissue approaches. Gene expression profiling of individual cells allows for unprecedented access to cell types that comprise only a small percentage of the total tissue1-7. In addition, this technique can be used to examine the gene expression programs that are transiently expressed in small numbers of cells during dynamic developmental transitions8.
This issue of cellular diversity arises repeatedly in the central nervous system (CNS) where neuronal connections can occur between quite diverse cells9. The exact number of distinct cell types is not precisely known, but it has been estimated that there may be as many as 1000 different types in the cortex itself10. The function(s) of complex neural circuits may rely on some of the rare neuronal types and the genes they express. By identifying new markers and helping to molecularly classify different neurons, the single-cell approach is particularly useful in the analysis of cell types in the nervous system. It may also help to elucidate mechanisms of neural development by identifying differentially expressed genes and gene pathways during early stages of neuronal progenitor development.
As a simple, easily accessed tissue with considerable neuronal diversity, the vertebrate retina is an excellent model system for studying the processes of cellular development, neuronal differentiation and neuronal diversification. However, as in other parts of the CNS, this cellular diversity can present a problem for determining the genetic pathways that drive retinal progenitors to adopt a specific cell fate, especially given that rod photoreceptors make up the majority of the total retinal cell population11. Here we report a method for the identification of the transcripts expressed in single retinal cells (Figure 1). The single-cell profiling technique allows for the assessment of the amount of heterogeneity present within different cellular populations of the retina2,4,5,12. In addition, this method has revealed a host of new candidate genes that may play role(s) in the cell fate decision-making processes that occur in subsets of retinal progenitor cells8. With some simple adjustments to the protocol, this technique can be utilized for many different tissues and cell types.

A method for the isolation of single retinal cells and subsequent amplification of their cDNAs is described. Single-cell transcriptomics reveals the degree of cellular heterogeneity present in a tissue and uncovers new marker genes for rare cell populations. The accompanying protocol can be adjusted to suit many different cell types.

Una sola célula de perfiles de neuronas de la retina en desarrollo y maduro

Highly specialized, but exceedingly small populations of cells play important roles in many tissues. The identification of cell-type specific markers and ...

Isolation and Culture of Neural Crest Cells from Embryonic Murine Neural Tube

The embryonic neural crest (NC) is a multipotent progenitor population that originates at the dorsal aspect of the neural tube, undergoes an epithelial to mesenchymal transition (EMT) and migrates throughout the embryo, giving rise to diverse cell types 1-3. NC also has the unique ability to influence the differentiation and maturation of target organs4-6. When explanted in vitro, NC progenitors undergo self-renewal, migrate and differentiate into a variety of tissue types including neurons, glia, smooth muscle cells, cartilage and bone. 
NC multipotency was first described from explants of the avian neural tube7-9. In vitro isolation of NC cells facilitates the study of NC dynamics including proliferation, migration, and multipotency. Further work in the avian and rat systems demonstrated that explanted NC cells retain their NC potential when transplanted back into the embryo10-13. Because these inherent cellular properties are preserved in explanted NC progenitors, the neural tube explant assay provides an attractive option for studying the NC in vitro. 
To attain a better understanding of the mammalian NC, many methods have been employed to isolate NC populations. NC-derived progenitors can be cultured from post-migratory locations in both the embryo and adult to study the dynamics of post-migratory NC progenitors11,14-20, however isolation of NC progenitors as they emigrate from the neural tube provides optimal preservation of NC cell potential and migratory properties13,21,22. Some protocols employ fluorescence activated cell sorting (FACS) to isolate a NC population enriched for particular progenitors11,13,14,17. However, when starting with early stage embryos, cell numbers adequate for analyses are difficult to obtain with FACS, complicating the isolation of early NC populations from individual embryos. Here, we describe an approach that does not rely on FACS and results in an approximately 96% pure NC population based on a Wnt1-Cre activated lineage reporter23. 
The method presented here is adapted from protocols optimized for the culture of rat NC11,13. The advantages of this protocol compared to previous methods are that 1) the cells are not grown on a feeder layer, 2) FACS is not required to obtain a relatively pure NC population, 3) premigratory NC cells are isolated and 4) results are easily quantified. Furthermore, this protocol can be used for isolation of NC from any mutant mouse model, facilitating the study of NC characteristics with different genetic manipulations. The limitation of this approach is that the NC is removed from the context of the embryo, which is known to influence the survival, migration and differentiation of the NC2,24-28.

Isolation of embryonic neural crest from the neural tube facilitates the use of in vitro methods for studying migration, self-renewal, and multipotency of neural crest.

Aislamiento y cultivo de células de la cresta neural de embriones murinos del Tubo Neural

The embryonic neural crest (NC) is a multipotent progenitor population that originates at the dorsal aspect of the neural tube, undergoes an epithelial to ...

A Quantitative Cell Migration Assay for Murine Enteric Neural Progenitors

Neural crest cells (NCC) are a transient and multipotent cell population that originates from the dorsal neural tube and migrates extensively throughout the developing vertebrate embryo. In addition to providing peripheral glia and neurons, NCC generate melanocytes as well as most of the cranio-facial skeleton. NCC migration and differentiation is controlled by a combination of their axial origin along the neural tube and their exposure to regionally distinct extracellular cues. Such contribution of extracellular ligands is especially evident during the formation of the enteric nervous system (ENS), a complex interconnected network of neural ganglia that locally controls (among other things) gut muscle movement and intestinal motility. Most of the ENS is derived from a small initial pool of NCC that undertake a long journey in order to colonize - in a rostral to caudal fashion - the entire length of the prospective gut. Among several signaling pathways known to influence enteric NCC colonization, GDNF/RET signaling is recognized as the most important. Indeed, spatiotemporally controlled secretion of the RET ligand GDNF by the gut mesenchyme is chiefly responsible for the attraction and guidance of RET-expressing enteric NCC to and within the embryonic gut. Here, we describe an ex vivo cell migration assay, making use of a transgenic mouse line possessing fluorescently labeled NCC, which allows precise quantification of enteric NCC migration potential in the presence of various growth factors, including GDNF.

We present an ex vivo cell migration assay that allows precise quantification of enteric neural crest cell migration potential in the presence of various growth factors.

Un ensayo de migración celular cuantitativa para murinos entéricas Neuronales Progenitores

Neural crest cells (NCC) are a transient and multipotent cell population that originates from the dorsal neural tube and migrates extensively throughout ...

Laser Nanosurgery of Cerebellar Axons In Vivo

Only a few neuronal populations in the central nervous system (CNS) of adult mammals show local regrowth upon dissection of their axon. In order to understand the mechanism that promotes neuronal regeneration, an in-depth analysis of the neuronal types that can remodel after injury is needed. Several studies showed that damaged climbing fibers are capable of regrowing also in adult animals1,2. The investigation of the time-lapse dynamics of degeneration and regeneration of these axons within their complex environment can be performed by time-lapse two-photon fluorescence (TPF) imaging in vivo3,4. This technique is here combined with laser surgery, which proved to be a highly selective tool to disrupt fluorescent structures in the intact mouse cortex5-9.
This protocol describes how to perform TPF time-lapse imaging and laser nanosurgery of single axonal branches in the cerebellum in vivo. Olivocerebellar neurons are labeled by anterograde tracing with a dextran-conjugated dye and then monitored by TPF imaging through a cranial window. The terminal portion of their axons are then dissected by irradiation with a Ti:Sapphire laser at high power. The degeneration and potential regrowth of the damaged neuron are monitored by TPF in vivo imaging during the days following the injury.

Laser Nanosurgery of Cerebellar Axons In Vivo

Two-photon imaging, coupled to laser nanodissection, are useful tools to study degenerative and regenerative processes in the central nervous system with subcellular resolution. This protocol shows how to label, image, and dissect single climbing fibers in the cerebellar cortex in vivo.

Laser Nanocirugía del cerebelo Los axones<em&gt; En Vivo</em

Only a few neuronal populations in the central nervous system (CNS) of adult mammals show local regrowth upon dissection of their axon. In order to ...

Live Imaging of Nicotine Induced Calcium Signaling and Neurotransmitter Release Along Ventral Hippocampal Axons

Sustained enhancement of axonal signaling and increased neurotransmitter release by the activation of pre-synaptic nicotinic acetylcholine receptors (nAChRs) is an important mechanism for neuromodulation by acetylcholine (ACh). The difficulty with access to probing the signaling mechanisms within intact axons and at nerve terminals both in vitro and in vivo has limited progress in the study of the pre-synaptic components of synaptic plasticity. Here we introduce a gene-chimeric preparation of ventral hippocampal (vHipp)&#8211;accumbens (nAcc) circuit in vitro that allows direct live imaging to analyze both the pre- and post-synaptic components of transmission while selectively varying the genetic profile of the pre- vs post-synaptic neurons. We demonstrate that projections from vHipp microslices, as pre-synaptic axonal input, form multiple, reliable glutamatergic synapses with post-synaptic targets, the dispersed neurons from nAcc. The pre-synaptic localization of various subtypes of nAChRs are detected and the pre-synaptic nicotinic signaling mediated synaptic transmission are monitored by concurrent electrophysiological recording and live cell imaging. This preparation also provides an informative approach to study the pre- and post-synaptic mechanisms of glutamatergic synaptic plasticity in vitro.

We developed a gene-chimeric preparation of ventral hippocampal &#8211; accumbens circuit in vitro that allows direct live imaging to analyze presynaptic mechanisms of nicotinic acetylcholine receptors (nAChRs) mediated synaptic transmission. This preparation also provides an informative approach to study the pre- and post-synaptic mechanisms of synaptic plasticity.

Imágenes en vivo de nicotina señalización de calcio inducido y neurotransmisor lanzamiento Junto ventrales hipocampo axones

Sustained enhancement of axonal signaling and increased neurotransmitter release by the activation of pre-synaptic nicotinic acetylcholine receptors ...

In Vivo Gene Transfer to Schwann Cells in the Rodent Sciatic Nerve by Electroporation

The formation of the myelin sheath by Schwann cells (SCs) is essential for rapid conduction of nerve impulses along axons in the peripheral nervous system. SC-selective genetic manipulation in living animals is a powerful technique for studying the molecular and cellular mechanisms of SC myelination and demyelination in vivo. While knockout/knockin and transgenic mice are powerful tools for studying SC biology, these methods are costly and time consuming. Viral vector-mediated transgene introduction into the sciatic nerve is a simpler and less laborious method. However, viral methods have limitations, such as toxicity, transgene size constraints, and infectivity restricted to certain developmental stages. Here, we describe a new method that allows selective transfection of myelinating SCs in the rodent sciatic nerve using electroporation. By applying electric pulses to the sciatic nerve at the site of plasmid DNA injection, genes of interest can be easily silenced or overexpressed in SCs in both neonatal and more mature animals. Furthermore, this in vivo electroporation method allows for highly efficient simultaneous expression of multiple transgenes. Our novel technique should enable researchers to efficiently manipulate SC gene expression, and facilitate studies on SC development and function.

In Vivo Gene Transfer to Schwann Cells in the Rodent Sciatic Nerve by Electroporation

Here, we present an in vivo technique for gene transfer to Schwann cells (SCs) in the rodent sciatic nerve. This simple technique is useful for investigating signaling mechanisms involved in the development and maintenance of myelinating SCs.

En Vivo Transferencia de genes a células de Schwann en el nervio ciático de roedores mediante electroporación

The formation of the myelin sheath by Schwann cells (SCs) is essential for rapid conduction of nerve impulses along axons in the peripheral nervous ...

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat open surfaces is complex,&#160;including: pausing, turning, and meandering. This complexity in the repertoire of movement hinders detailed analysis of the events occurring during a single crawl stride cycle. To overcome this obstacle, linear agarose channels were made that constrain larval behavior to straight, sustained, rhythmic crawling. In principle, because agarose channels and the Drosophila larval body are both optically clear, the movement of larval structures labeled by genetically-encoded fluorescent probes can be monitored in intact, freely-moving larvae. In the past, larvae were placed in linear channels and crawling at the level of whole organism, segment, and muscle were analyzed1. In the future, larvae crawling in channels can be used for calcium imaging to monitor neuronal activity. Moreover, these methods can be used with larvae of any genotype and with any researcher-designed channel. Thus the protocol presented below is widely applicable for studies using the Drosophila larva as a model to understand motor control.

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

The Drosophila larva is a powerful model system to study neural control of behavior. This publication describes the use of linear agarose channels to elicit sustained bouts of linear crawling and methods to quantify the dynamics of larval structures during repetitive crawling behavior.

Uso de los canales lineales de agarosa para estudiar<em&gt; Drosophila</em&gt; Comportamiento de las larvas de arrastre

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat ...

Analyzing Dendritic Morphology in Columns and Layers

In many regions of the central nervous systems, such as the fly optic lobes and the vertebrate cortex, synaptic circuits are organized in layers and columns to facilitate brain wiring during development and information processing in developed animals. Postsynaptic neurons elaborate dendrites in type-specific patterns in specific layers to synapse with appropriate presynaptic terminals. The fly medulla neuropil is composed of 10 layers and about 750 columns; each column is innervated by dendrites of over 38 types of medulla neurons, which match with the axonal terminals of some 7 types of afferents in a type-specific fashion. This report details the procedures to image and analyze dendrites of medulla neurons. The workflow includes three sections: (i) the dual-view imaging section combines two confocal image stacks collected at orthogonal orientations into a high-resolution 3D image of dendrites; (ii) the dendrite tracing and registration section traces dendritic arbors in 3D and registers dendritic traces to the reference column array; (iii) the dendritic analysis section analyzes dendritic patterns with respect to columns and layers, including layer-specific termination and planar projection direction of dendritic arbors, and derives estimates of dendritic branching and termination frequencies. The protocols utilize custom plugins built on the open-source MIPAV (Medical Imaging Processing, Analysis, and Visualization) platform and custom toolboxes in the matrix laboratory language. Together, these protocols provide a complete workflow to analyze the dendritic routing of Drosophila medulla neurons in layers and columns, to identify cell types, and to determine defects in mutants.

Here, we show how to analyze dendritic routing of Drosophila medulla neurons in columns and layers. The workflow includes a dual-view imaging technique to improve the image quality and computational tools for tracing, registering dendritic arbors to the reference column array and for analyzing the dendritic structures in 3D space.

Analizando dendríticas morfología en las columnas y capas

In many regions of the central nervous systems, such as the fly optic lobes and the vertebrate cortex, synaptic circuits are organized in layers and ...

Spectral Reflectometric Microscopy on Myelinated Axons In Situ

In a mammalian nervous system, myelin provides an electrical insulation by enwrapping the axon fibers in a multilayered spiral. Inspired by its highly-organized subcellular architecture, we recently developed a new imaging modality, named spectral reflectometry (SpeRe), which enables unprecedented label-free nanoscale imaging of the live myelinated axons in situ. The underlying principle is to obtain nanostructural information by analyzing the reflectance spectrum of the multilayered subcellular structure. In this article, we describe a detailed step-by-step protocol for performing a basic SpeRe imaging of the nervous tissues using a commercial confocal microscopic system, equipped with a white-light laser and a tunable filter. We cover the procedures of sample preparation, acquisition of spectral data, and image processing for obtaining nanostructural information.

Spectral Reflectometric Microscopy on Myelinated Axons In Situ

Here, we present a step-by-step protocol for imaging myelinated axons in a fixed brain slice using a label-free nanoscale imaging technique based on spectral reflectometry.